Power source device for boat

ABSTRACT

To maintain stabilized operation of a boat engine, a propulsion device may be provided with two separate batteries for different uses in case one of the batteries suffers a voltage drop. A power source device is provided with a propulsion battery for supplying power to engine-related components of an outboard motor and an auxiliary battery for supplying power to boat accessories. An anomaly time power supply circuit is connected to the power supply route of the propulsion battery and the power supply route of the auxiliary battery. Electric power from the auxiliary battery is supplied to the engine-related components when the charged voltage of the propulsion battery lowers below the charged voltage of the auxiliary battery, so that power to the engine-related components is supplemented in order to maintain stabilized operation of the engine.

PRIORITY INFORMATION

This application claims priority from Japanese Patent Application No. 2004189639, filed Jun. 28, 2004, the entire contents of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a power source device for supplying power to a propulsion device on a boat, such as, for example, an outboard motor.

2. Description of the Related Art

Boats often have two batteries for different operations and requirements of the boat's propulsion and auxiliary power needs. A large capacity battery is used for the supplying power to the engine and other engine components, such as the starting motor, ignition device, etc. The large capacity battery is used to initiate operation of the engine by turning the starting motor and operating the ignition devices to start an internal combustion engine, for example. A smaller capacity battery is also used for supplying power to peripheral devices or accessories, such as a navigation lamp or instrument panel.

When the large and small capacity batteries drop in voltage, the batteries may be recharged by a generator, such as an alternator, that supplies power to the batteries when the engine is operating. The boats also contain a power regulation device that permits the generator to recharge the batteries to their full capacity during operation of the engine.

SUMMARY OF THE INVENTION

An aspect of the present invention involves the recognition that in prior power regulation devices with two boat batteries and two separate electric power supply routes, one battery cannot supplement the other battery if a voltage drop occurs in the first battery. Because most propulsion devices employ a fuel injector, interruption of electric power to the fuel injector may prevent fuel from being injected into the engine, which may cause the engine to stop operating. If a voltage drop occurs in the propulsion battery or a wire breaks in the battery power supply circuit while the engine is in operation, power supply to the engine is provided by the generator, which may lead to instability of the power source and failure of the engine should the generator be unable to consistently provide the required power.

Accordingly, disclosed herein is a power source device that is capable of providing a continued stabilized driving state of the propulsion device by supplementing the power of one battery with the power of another battery should a voltage drop occur in the first battery.

In accordance with one aspect of the invention, the power source device for the boat may comprise a propulsion battery for supplying electric power to a propulsion device of the boat and an auxiliary battery for supplying electric power to other devices of the boat. The power source device may also include an anomaly time power supply circuit for supplying electric power from the auxiliary battery when a voltage drop occurs in the propulsion battery.

In accordance with another aspect, the power source device may comprise a propulsion battery for supplying electric power to a propulsion device of the boat, an auxiliary battery for supplying electric power to auxiliary devices of the boat, an anomaly time power supply circuit for supplying electric power from the auxiliary battery when a voltage drop occurs in the propulsion battery, a voltage detecting means for individually detecting the voltages of the propulsion battery and the auxiliary battery, and an anomaly processing section for performing an anomaly processing action when a battery anomaly is detected based on the voltages of the propulsion battery and the auxiliary battery detected with the voltage detecting means.

In accordance with another aspect, a power source device for a boat is provided. The power source device may comprise a propulsion battery for supplying electric power to a propulsion device of the boat and an auxiliary battery for supplying electric power to auxiliaries of the boat. The power source device may also comprise a power supply circuit for supplying electric power from the auxiliary battery when a voltage drop occurs in the propulsion battery and an anomaly processing section that is configured to detect voltages of the propulsion battery and the auxiliary battery. The anomaly processing section may be configured to detect at least one of the following power source anomalies: a low battery voltage in the auxiliary battery, a low battery voltage in the propulsion battery, a parallel connection, and a broken wire. When the anomaly processing section detects a low battery voltage in the propulsion battery, the anomaly processing section may increase the output of a generator.

A method is also provided for controlling a boat's power supply when the boat has a plurality of batteries and a generator. The method may comprise detecting the voltage of a propulsion battery and comparing the detected voltage with a first threshold propulsion battery voltage. The method may also comprise supplementing the voltage of the propulsion battery with the voltage of the auxiliary battery when the voltage of the propulsion battery falls below the first threshold propulsion battery voltage. The method also comprises determining whether a drop in propulsion battery voltage is caused by a broken wire or low battery voltage when the propulsion battery voltage falls below the first threshold propulsion battery voltage, and providing at least one of an audible and visual signal that either a low battery voltage or a broken wire exists and increased generator output when the cause of the drop in propulsion battery voltage is determined.

In accordance with yet another aspect of the invention, a power source device for a boat is provided. The power source device preferably comprises a propulsion battery for supplying electric power to a propulsion device of the boat, and an auxiliary battery for supplying electric power to auxiliaries of the boat. The power source device also preferably comprises means for supplying electric power from the auxiliary battery when a voltage drop occurs in the propulsion battery, and means for detecting at least one of the following power source anomalies: a low battery voltage in the auxiliary battery, a low battery voltage in the propulsion battery, a parallel connection, and a broken wire. Additionally, when a low battery voltage is detected in the propulsion battery, the output of a generator is increased.

For purposes of summarizing the invention, certain aspects, advantages, and features of the invention have been described herein. It is to be understood that not necessarily all such aspects, advantages, or features are required in any particular aspect of the invention. Additionally, it is to be understood that the above summary is not intended to limit in any way the aspects, advantages, or features described below in the Detailed Description of the Preferred Embodiments or the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an aspect of the invention.

FIG. 2 is a schematic view of an outboard motor of FIG. 1.

FIG. 3 is an electric circuit diagram of an aspect of a power source device of FIG. 2.

FIG. 4 is an electric circuit diagram of another aspect of a power source device.

FIG. 5 is a flowchart of a battery anomaly control process sequence in the engine control unit of FIG. 2.

FIG. 6 is an electric circuit diagram of another aspect of a power source device.

FIG. 7 is a flowchart of a battery anomaly control process sequence in the engine control unit of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the figures, certain aspects will be described, which aspects provide power supply devices for regulating the power supply from a propulsion battery and an auxiliary battery to reduce the likelihood of an unstable power supply should a voltage drop occur in the propulsion battery.

FIG. 1 illustrates a small boat 1 that may comprise a boat body 2 of an open deck type and an outboard motor 3 mounted on the stem of the boat body 2. In the front part of the boat body 2 are provided a steering wheel 4, a seat 5, a remote-control lever 6, and an operator's space provided with a switch panel 7 having, among other things, a main switch, a starting switch, and a meter panel 8.

As shown in FIG. 2, the outboard motor 3 is supported on the stem 2 a of the boat body 2 by means of a clamp bracket 21 to be swung up and down and swiveled horizontally. The outboard motor 3 comprises a propulsion device 22 housed in a lower case 23 on which is placed an engine 3E. The propulsion device 22 is configured such that a propeller shaft 26 is connected through a bevel gear mechanism 25 to the lower end of a driveshaft 24 extending vertically. A propeller 27 is attached to the rear end of the propeller shaft 26.

The bevel gear mechanism 25 is made up of a drive bevel gear 25 a attached to the drive shaft 24, and a forward bevel gear 25 b and a reverse bevel gear 25 c, both rotatably supported on the propeller shaft 26 and engaging with the drive bevel gear 25 a.

The propulsion device 22 is provided with a forward-reverse shift device 28 driven to rotate with an electric motor 28 a, a shift rod 28 b extending vertically, and a dog clutch 28 c connected to the shift rod 28 b. The dog clutch 28 c controls the shifting of the forward bevel gear 25 b and the reverse bevel gear 25 c so that either of them engages with the drive bevel gear 25 a to produce forward or reverse motion, or a neutral state is produced when neither of them engages the gear 25 a.

As shown in FIG. 2, the engine 3E may be a water-cooled, four-stroke cycle, six-cylinder, fuel injection type, with a crankshaft 30 placed vertically so as to be nearly vertical when the boat runs. The lower end of the crankshaft 30 is connected to the upper end of a drive shaft 24. The engine 3E comprises a cylinder block 31 provided with cylinders 31 a in which pistons 32 are inserted, with the pistons 32 connected through connecting rods 33 to the crankshaft 30.

A cylinder head 34 is tightened to the back face, as seen in the longitudinal direction of the boat, of the cylinder block 31. An ignition plug 35 is attached to the combustion chamber 34 a formed with each cylinder 31 a and the cylinder head 34. An exhaust port 36 and an intake port 37 in communication with each combustion chamber 34 a are respectively provided with an exhaust valve 38 and an intake valve 39 which are driven to open and close with camshafts 40 and 41 placed parallel to the crankshaft 30. Also shown are an ignition coil 35 a and an igniter 35 b.

The exhaust ports 36 are connected to an exhaust manifold 42 so that exhaust gas flows through a lower case 23 from the exhaust manifold 42 and is discharged out of the rear end of the propulsion device 22. Each intake port 37 is connected to an intake pipe 43 within which is provided an electronically controlled throttle valve 44. A fuel injection valve 45 is inserted in part of the cylinder head 34 facing each intake port 37, with the injection nozzle of the fuel injection valve 45 directed to the opening of each intake port 37.

Fuel is supplied through a fuel supply system 12 placed in the stem 2 a of the boat body 2 to the fuel injection valves 45. The fuel supply system 12 is constituted that fuel in a fuel tank 12 a placed in the stern 2 a of the boat body 2 is supplied to a vapor separator tank 12 c placed on the engine side using a fuel pump 12 b and that the fuel in this tank 12 c is supplied to the fuel injection valve 45 using a high pressure pump 12 d.

The engine 3E is provided with an engine control means, or an engine control unit 46, constituted with a microcomputer or the like. The engine control unit 46 receives input of values detected with an engine speed sensor 47 for detecting the rotary speed of the crankshaft 30, an intake pressure sensor 48, a throttle opening sensor 49, an engine temperature sensor 50, and a cylinder discriminating sensor 51. The engine control unit 46 also receives input of the boat speed value detected with a boat speed sensor (not shown) and the throttle opening command value that is chosen with the remote-control lever 6, through a bus 15 constituting a local area network. A start signal ST is supplied from a start switch on the switch panel 7 to a starter relay 52. When a starting motor 54 is made operative with a starting circuit 53, the engine control unit 46 starts the engine 3E while controlling the fuel injection rate, timing of the fuel injection valves 45, and the ignition timing of the ignition plugs 35 based on the detected engine speed and other detected values. The engine control unit 46 controls the engine speed based on the detected values and in accordance with a pre-stored operation control map. The crankshaft 30 is connected to a generator, which may be an alternator.

The electric motor 28 a of the forward-reverse shift device 28 is driven to rotate with a shift control unit 60, which may be a microcomputer, for example. When one of the forward, reverse, and neutral positions is chosen with the remote control lever 6, shift position data corresponding to the chosen position is transmitted through the data bus 15 to the shift control unit 60. When the shift position denotes the forward position, the shift control unit 60 operates the dog clutch 28 c by rotating the shift rod 28 b so that the forward bevel gear 25 b engages with the drive bevel gear 25 a. When the shift position denotes the reverse position, the shift control unit 60 operates the dog clutch 28 c by rotating the shift rod 28 b so that the reverse bevel gear 25 c engages with the drive bevel gear 25 a. When the shift position detection data denotes the neutral position, the shift control unit 60 rotates the shift rod 28 b so that both the forward bevel gear 25 b and the reverse bevel gear 25 c are disengaged from the drive bevel gear 25 a.

As shown in FIG. 3, power is supplied from a power source device 70 to the fuel pump 12 b and the high pressure pump 12 d of the fuel supply system 12, the igniter 35 b, the engine control unit 46, the starter relay 52, and the shift control unit 60.

As illustrated in FIG. 3, the power source device 70 may comprise a propulsion battery 71 of a relatively large capacity for supplying electricity to a propulsion driving system 61 including the fuel supply system 12, the igniter 35 b, the engine control unit 46, the starter relay 52, and the shift control unit 60, and an auxiliary battery 73 of a relatively. small capacity for supplying electricity to boat accessories 72, having individual switches, such as a navigation lamp and an instrument panel.

The propulsion battery 71 preferably has its negative pole grounded, and its positive pole is preferably connected through a main switch 74 to the starter relay 52 and the igniter 35 b. The positive pole is also preferably connected to the fuel supply system 12, engine control unit 46, and the shift control unit 60 through the main switch 74 and a diode D1 for preventing roundabout current.

The auxiliary battery 73 preferably has its negative pole grounded while its positive pole is preferably directly connected to the boat accessories 72, each having a built-in power source switch. The positive pole is also connected through a sub-switch 75 interlocking with the main switch 74 and a diode D2 for supplying power to the fuel supply system 12, the engine control unit 46, and the shift control unit 60. Diode D2 operates in the above arrangement to prevent roundabout current. The diodes D1 and D2 for preventing roundabout current constitute an anomaly time power supply circuit 76.

The power from the generator 55 flows through a full-wave rectification circuit 77 and through diodes D3 and D4 to a connection line between the main switch 74 and the anode of diode D1 and to another connection line between the sub-switch 75 and the anode of diode D2. This arrangement permits the generator 55 to charge the propulsion battery 71 and the auxiliary battery 73 with power generated, and the arrangement also permits the generator 55 to supply power to the fuel pump 12 b and the high pressure pump 12 d of the fuel supply system 12, the igniter 35 b, the engine control unit 46, the starter relay 52, and the shift control unit 60.

In accordance with one aspect, and as illustrated in FIG. 3, it is assumed that charged voltages Vp and Vs of the propulsion battery 71 and the auxiliary battery 73 of the power source device 70 are both in the normal state and above a threshold voltage Vh. In this state, if the main switch 74 is off, the sub-switch 75 interlocking with it is also off. Therefore, no electric power is supplied to the propulsion device operating systems, which include the fuel pump 12 b and the high pressure pump 12 c of the fuel supply system 12, the igniter 35 b, the engine control unit 46, the starter relay 52, and the shift control unit 60, and also no power is supplied to the boat accessories 72.

When the main switch 74 is turned on in the above state, the sub-switch 75 interlocking with it is also turned on. The power of the propulsion battery 71 is supplied through the main switch 74 to the starter relay 52, through the diode D1 to the fuel pump 12 b and the high pressure pump 12 d of the fuel supply system 12, the igniter 35 b, and further to the engine control unit 46 and the shift control unit 60 so that these devices are able to operate. The electric power of the auxiliary battery 73 is also supplied to the boat accessories 72.

Therefore, when power switches built in the boat accessories 72 are turned on, electric power is supplied to the navigation lamp, the instrument panel, etc. When the starting switch is turned on for a required period of time, the starter relay 52 is turned on to supply electric power to the starting circuit 53. As a result, the starting motor 54 is driven to rotate the crankshaft 30. At the same time, the engine 3E is started while ignition timing of the ignition plugs 35 and igniter 35 b is controlled with the engine control unit 46 according to the engine revolution detected with the engine speed sensor 47.

When the engine 3E is started in this way, electricity generated with the generator 55 is supplied through the full-wave rectification circuit 77 and the diodes D3 and D4 between the propulsion device operating systems and the propulsion battery 71 and between the boat accessories 72 and the auxiliary battery 73. Therefore, when the voltage of the generated electric power exceeds the charged voltages of the propulsion battery 71 and the auxiliary battery 73 and when the generated electric power exceeds the electric power consumed with the propulsion device operating systems and the boat accessories 72, the propulsion battery 71 and the auxiliary battery 73 are charged with the surplus electric power.

If the propulsion battery 71 runs down and its charged voltage becomes lower than the charged voltage of the auxiliary battery 73, the voltage potential following diode D1 will likewise decrease, permitting diode D2 to become active and permit current to flow therethrough. Accordingly, electric power from the auxiliary battery 73 is supplied through diode D2 to the fuel pump 12 b and the high pressure pump 12 d of the fuel supply system 12, the engine control unit 46, and the shift control unit 60, so that it is possible to secure stabilized electric power supply to the fuel supply system and maintain favorable fuel injection out of the fuel injection valves 45 while the engine 3E is in operation. Because electric power generated with the generator 55 is supplied to the igniter 35 b, timing control of the ignition plugs 35 is effected as usual to continue operating condition of the engine 3E.

When the wire breaks between the propulsion battery 71 and the interconnection point of the diodes D1 and D3, so that electric power cannot be supplied from the propulsion battery 71 to the propulsion device operating systems, it is possible to supply electric power from the auxiliary battery 73 through the diode D2 and maintain normal operation of the engine 3E. Accordingly, should the voltage of the propulsion battery 71 lower or the wire breaks between the propulsion battery 71 and the propulsion device operating systems so that adequate power cannot be supplied to the fuel supply system 12 and the control units 46 and 60, power can be supplied from the auxiliary battery 73 through the anomaly time power supply circuit 76 made up of the diodes D1 and D2. This will permit that at least operation of fuel injection can be maintained.

A second aspect is illustrated in FIG. 4 that is adapted to monitor the charged voltages of the propulsion battery 71 and the auxiliary battery 73 and to implement anomaly processing such as sounding an alarm when a voltage drop anomaly of the propulsion battery 71 is detected.

As shown in FIG. 4, voltages of the propulsion battery 71 and the auxiliary battery 73 of the power source device 70 are inputted to A/D conversion input terminals AD1 and AD2 of the engine control unit 46, which monitors the voltages of both the batteries 71 and 73 and detects anomaly. The anomaly, when detected, is processed according to its mode.

According to one aspect, the engine control unit 46 performs a power source anomaly control process to test for anomalies in the power supply, as shown in FIG. 5. While in the preferred aspect, the power source anomaly control process is performed by the engine control unit 46, it is contemplated that the process may be performed by a separate component or controller.

The power source anomaly control process preferably begins with step S1, where voltages Vp and Vs of the propulsion battery 71 and the auxiliary battery 73 are read. Additionally, Next in step S2, a determination is made whether the voltage Vp of the propulsion battery 71 has lowered below a predetermined threshold voltage Vpt. If Vp>Vpt, or the voltage Vp is not lower than or equal to the predetermined threshold voltage Vpt, it is tentatively regarded that the voltage Vp is sufficient and the propulsion battery 71 is normal.

In comparing the voltages, it is contemplated that analog circuitry may be used as well as digital logic. Additionally, while the lines of communication between sensors that determine the voltage and the engine control unit 46 are illustrated as being hard-wired, it is contemplated that the information may also be communicated through a local area network (LAN). For example, the information could be communicated through the LAN by hard-wire or wireless (e.g., RF or infrared).

The process then proceeds with step S3, in which a determination is made whether the voltage Vs of the auxiliary battery 73 is lower than a predetermined threshold voltage Vst. If Vs>Vst, or the voltage Vs is not lower than or equal to the predetermined threshold voltage Vst, it is tentatively regarded that the voltage Vs is sufficient and the auxiliary battery 73 is normal. The process goes on to step S4.

In step S4, a determination is made whether the absolute value |ΔV| of the voltage difference ΔV from the voltage Vp of the propulsion battery 71 and the voltage Vs of the auxiliary battery 73 is not greater than a predetermined value ΔVx, or difference threshold, continuously for a predetermined period of time (for example about one minute). If the absolute value |ΔV| of the voltage difference ΔV is held not greater than a predetermined value ΔVx for the predetermined period of time, it is determined that a parallel connection anomaly is present in which the positive poles of the propulsion battery 71 and the auxiliary battery 73 are directly interconnected in parallel by mistake. The process goes on to step S5 in which a guidance information indicating the parallel connection anomaly or anomaly display information is displayed on a liquid crystal display (LCD) 80, which may be provided on the switch panel 7. At the same time, an alarm signal may be outputted to a speaker 81 that may likewise be provided near the switch panel 7. The process then goes back to step S1. In the case the absolute value |ΔV| of the voltage difference ΔV is greater than the predetermined value ΔVx, it is determined to be a normal state in which the positive poles of the propulsion battery 71 and the auxiliary battery 73 are isolated from each other, and the process returns directly to the step S1.

If the determination in step S2 results in Vp≦Vpt, or the voltage Vp is equal to or less than the predetermined threshold voltage Vpt, it is regarded that the voltage Vp of the propulsion battery 71 is insufficient. The process goes to step S6 and a determination is made whether the voltage Vp of the propulsion battery 71 is not greater than a broken wire threshold voltage Vpc, which is preferably near “zero.” If the determination results in Vp>Vpc, or the voltage Vp is greater than the threshold voltage Vpc, the propulsion battery 71 is determined to be in a low voltage state due to insufficient charged voltage or the like, and the process goes on to step S7 in which guidance information or anomaly display information denoting a low battery voltage anomaly is displayed on the LCD 80, and an alarm is outputted to the speaker 81. The process proceeds to step S8, a process of increasing generated electricity, in which the engine speed is increased to provide an increased amount of generated electricity by the generator 55 to recharge the propulsion battery 71. The process then returns to step S1.

If the determination in the above step S6 results in the voltage Vp of the propulsion battery 71 is not greater than the broken wire threshold voltage Vpc, it is regarded that a broken wire or short circuit has occurred in the electric power supply route between the propulsion battery 71 and the A/D conversion input terminal AD1 of the engine control unit 46, and the process goes on to step S9 in which guidance information denoting a broken wire or short circuit, or broken wire anomaly display information, is outputted to the LCD 80, and an alarm signal is supplied to the speaker 81. Then, the process goes on to step S8 described above.

Furthermore, if the determination in step S3 results in the voltage Vs of the auxiliary battery 73 not greater than the threshold voltage Vst, it is regarded to be a low voltage anomaly of the auxiliary battery 73. The process goes on to step S10 in which guidance information or anomaly display information denoting a low voltage anomaly of the auxiliary battery 73 is outputted to the LCD 80, and an alarm signal is outputted to the speaker 81. Then, the process goes back to step S1.

In the process shown in FIG. 5, the voltage detecting means accomplishes the process of step S1 by the A/D conversion input terminal of the engine control unit 46, and the process of steps S2 to S10 corresponds to the anomaly processing section.

In accordance with another aspect, it may be assumed that the positive poles of the propulsion battery 71 and the auxiliary battery 73 are in the normal state as they are isolated and their voltages Vp and Vs are greater than the threshold voltages Vpt and Vst, respectively. When the main switch 74 is turned on, the sub-switch 75 is also turned on. Electric power is supplied to the engine control unit 46 to make it operative. The engine control unit 46 starts the engine control process by controlling the fuel supply system, ignition timing, and other devices and systems of the engine 3E. When the starting switch is turned on, the engine 3E is started. The engine control unit 46 controls throttle opening according to the throttle opening command value inputted from the remote-control lever 6.

Along with the above process, the engine control unit 46 performs a power source anomaly control process as shown in FIG. 5. Since the voltage Vp of the propulsion battery 71 and the voltage Vs of the auxiliary battery 73 are greater than the threshold voltages Vpt and Vst, the process moves on from step S1 through steps S2 and S3 to step S4. In step S4, because the positive poles of the propulsion battery 71 and the auxiliary battery 73 are isolated from each other, the power of the propulsion battery 71 is supplied to the starting motor, the fuel supply system, the engine operating system, and the other propulsion devices and systems while the power of the auxiliary battery 73 is supplied to the boat accessories 72. Therefore, the output voltages of both batteries 71, 73 may occasionally be relatively similar (e.g., while starting the engine), although they may not be similar for an extended period of time. While the similar voltages of the batteries 71, 73 may result in an indication of a parallel connection anomaly, the process may permit the voltages to be similar for a period of time. Accordingly, the process goes back to step S1 without indicating any anomaly display or giving out an alarm.

However, if the positive pole of the propulsion battery 71 is connected by mistake to the positive pole of the auxiliary battery 73 so that both the batteries are interconnected in parallel (e.g., during assembly of a new boat, new outboard motor 3, or replacement of the battery), the voltages Vp and Vs inputted to the A/D conversion input terminals AD1 and AD2 of the engine control unit 46 become relatively the same. Accordingly, the absolute value |ΔV| of the voltage difference ΔV becomes almost zero, which is not greater than the predetermined value ΔVx. As a result, the process moves on from step S4 to step S5 in which parallel connection anomaly display information denoting the parallel connection of the batteries is outputted to the LCD 80 and an alarm is sounded. Therefore, the operator can remove the parallel connection anomaly by turning off the main switch 75, checking the connected state of the propulsion battery 71 and the auxiliary battery 73 of the power source device 70, and reconnecting them so that the positive poles of the propulsion battery 71 and the auxiliary battery 73 are isolated from each other.

If the output voltage Vp of the propulsion battery 71 does not increase to become higher than the threshold voltage Vpt while the main switch 74 is turned on and held on, the process proceeds in accordance with the process illustrated in FIG. 5. Power from the auxiliary battery 73 may be supplied through the diode D2 to the fuel supply system and the engine control unit 46. The process shown in FIG. 5 moves from step S2 to step S6 to determine whether the output voltage Vp of the propulsion battery 71 is not higher than the broken wire threshold voltage Vpc. If Vp≦Vpc, or if the output voltage Vp of the propulsion battery 71 is not higher than the broken wire threshold voltage Vpc, it is determined that a broken wire or a short circuit is present in line with the propulsion battery 71. The process goes on to step S8, in which power from the generator 55 is increased to secure power for the drive system and the fuel supply system and for charging the auxiliary battery 73.

If the determination in step S6 is that Vp>Vpc, or that the output voltage Vp of the propulsion batter 71 is greater than the broken wire threshold voltage Vpc, it is determined that the propulsion battery 71 has deteriorated or power generated by the generator 55 is insufficient. Information on the anomaly in the propulsion battery 71 may be outputted to the LCD 80 to display the propulsion battery 71 anomaly, and an alarm signal is outputted to the speaker 81 to notify the operator by sounding an alarm. The process proceeds to step S8, in which power from the generator 55 is increased to secure power for the driving system and the fuel supply system and for charging the auxiliary battery 73.

If the output voltage Vp of the propulsion battery 71 is not higher than the threshold voltage Vpt but is high enough to rotate the starting motor 54 when the main switch 74 is activated, the engine 3E can be started, allowing the battery to be charged by increasing power generated with the generator 55. However, if the output voltage Vp of the propulsion battery 71 is low to the extent that cannot rotate the starting motor 54, the engine 3E cannot be started. The process shown in FIG. 5 goes to step S7 in which anomaly display for the propulsion battery 71 is shown, and an alarm is sounded, informing the operator that the propulsion battery 71 should be replaced. Because output voltage of the auxiliary battery 73 is supplied through diode D2 to the engine control unit 46, the process of FIG. 5 can be implemented as described.

Because a battery anomaly is displayed and an alarm is sounded when the charged voltage Vp of the propulsion battery 71 drops below the threshold voltage Vpt, it is possible to notify the operator of the anomaly of the propulsion battery 71 and make the operator aware of the power conditions so it may be checked when the boat comes back to the harbor.

Although the aspects have been described as operating with diodes D1 and D2, it is contemplated that diodes D1 and D2 may be replaced with semiconductor switching elements. The semiconductor switching elements may operate such that one of the elements is turned on based on an appropriate range of voltages of the propulsion battery 71.

In another aspect, the power source device 70 may be modified by replacing the diodes D1 and D2 with relay contact points. As shown in FIG. 6, the anomaly time power supply circuit 76 of the power source device 70 may be provided with a control relay 87 having relay contact points 85 that comprise a normally closed contact point tnc, a normally open contact point tno, a movable contact point tm, and a control relay 87 with a relay coil 86 for switching the movable contact point tm of the relay contact points 85. The normally closed contact point tnc of the relay contact points 85 is connected to the output side of the main switch 74, the normally open contact point tno is connected to the output side of the sub-switch 75, the movable contact point tm is connected to the fuel supply system 12 and to the power source input terminal pt of the engine control unit, and the relay coil 86 is connected to the output side of the engine control unit 46.

The engine control unit 46 implements the battery anomaly control process shown in FIG. 7. The battery anomaly control process of FIG. 7 is similar to the process shown in FIG. 5, with some differences. Therefore, the steps in FIG. 7 that correspond to those in FIG. 5 are provided with the same reference numerals and their detailed explanations are omitted. Steps S11, S12, S13, and S14 are interposed between steps S2 and S3, step S15 is interposed between steps S2 and S6, and step S16 is interposed between steps S6 and S7. The process includes a battery anomaly flag FS that provides an indication of the status of the battery. The battery anomaly flag FS may have two or more settings. In one aspect, the battery anomaly flag FS has a “1” and a “0” setting. The “1” setting denotes a low battery voltage state. Step S11 determines whether the battery anomaly flag FS is set to “1,” indicating a low battery voltage state. When the battery anomaly flag FS is set to “0,” the process jumps to step S14 described later. When Step S11 determines that the battery anomaly flag FS is set to “1,” the process moves to step S12, which determines whether the voltage of the propulsion battery 71 is higher than a threshold voltage Vpth, which is set to be higher than the threshold voltage Vpt. When step S12 results in Vp≦Vpth, or when the propulsion battery voltage Vp falls below the threshold voltage Vpth (and yet above threshold voltage Vpt in Step 2), Step S13 sets the anomaly flag FS to “0.” Step S14, following step S13, instructs the control relay 87 to shut off application of a predetermined current to the relay coil 86. When the voltage Vp of the propulsion battery 71 drops below the threshold voltage Vpt, the process proceeds to step 15. Step S15 switches the movable contact point tm of the relay contact points 85 to the normally open contact point tno. The step S16 sets the battery anomaly flag FS to “1” when the propulsion battery voltage Vp is above the broken wire threshold Vpc.

In the process shown in FIG. 7, the function of step S1 and the A/D conversion input terminal of the engine control unit 46 correspond to the voltage detecting means, and the functions of steps. S2 to S16 correspond to the anomaly processing section.

In FIG. 7, it is assumed that the propulsion battery 71 and the auxiliary battery 73 are in the normal state with voltages Vp and Vs higher than the respective threshold voltages Vpt and Vst. When the main switch 74 is activated, because no power is supplied to the engine control unit 46 and the relay coil 86 of the control relay 87 is not energized, the movable contact point tin of the relay contact points 85 remains in its default state againt the normally closed contact point tnc. Therefore, power of the propulsion battery 71 is supplied to the power source input terminal pt of the engine control unit 46 through the main switch 74, the normally closed contact point tnc, and the movable contact point tm of the relay contact points 85, so that the engine control unit 46 becomes operative. Therefore, the engine control process is started with the engine control unit 46. When the starting switch is turned on, the engine 3E starts to rotate at a revolution with a throttle opening corresponding to the chosen position of the remote-control lever 6.

The battery anomaly control process shown in FIG. 7 may also be started. Because the propulsion battery 71 is normal, the process moves from step S2 to step S11 to maintain the shut-off state of the predetermined value of current to the relay coil 86 of the control relay 87 and to maintain the position of the movable contact point tm to the side of the normally closed contact point tnc. As a result, power from the propulsion battery 71 is supplied to the fuel supply system 12, the igniter 35 b, the engine control unit 46, the starter relay 52, and the shift control unit 60, so that they function normally. Because power from the propulsion battery 71 is supplied through the normally closed contact point tnc and the movable contact point tm of the control relay 86 to the fuel supply system 12 to the igniter 35 c and to the engine control unit 46, no voltage drop occurs between the normally closed contact point tnc and the movable contact point tm. Therefore, the life of the propulsion battery 71 can be increased by reducing the power loss that may result when power is supplied through the diode D1, shown in FIGS. 3 and 4.

When the voltage of electric power from the generator 55 exceeds the charged voltages Vp and Vs of the propulsion battery 71 and the auxiliary battery 73, the electric power is supplied through the diodes D3 and D4 to the starter relay 52, the fuel supply system 12, the igniter 35 b, the engine control unit 46, and the shift control unit 60, so that surplus electric power charges the propulsion battery 71 and the auxiliary battery 73.

When the propulsion battery 71 changes from the normal state to the low battery voltage anomaly state, in which the output voltage Vp is not higher than the threshold voltage Vpt, the process shown in FIG. 7 moves from step S2 to step S15, in which a predetermined value of current is supplied to the relay coil 85 of the control relay 86. As a result, the movable contact point tm is switched to the normally open contact point tno. Therefore, in place of the propulsion battery 71, the auxiliary battery 73 supplies electric power to the fuel supply system 12, the igniter 35 b, the engine control unit 46, and the shift control unit 60 to maintain the operationg of the engine.

When the output voltage Vp of the propulsion battery 71 is higher than the broken wire threshold voltage Vpc, the process goes to step S16 to set the battery anomaly flag FS to “1” and moves on to the step S7 to show an anomaly display for the propulsion battery on the LCD 80 and to sound an alarm from the speaker 81. Further in step S8, the speed of the engine 3E is increased to increase the output of the generator 55. Therefore, the propulsion battery 71 and the auxiliary battery 73 are able to be charged by the generator 55. When the output voltage Vp of the propulsion battery 71 is not higher than the broken wire threshold voltage Vpc, the process goes to step S9 to show a display of broken wire anomaly for the propulsion battery 71 on the LCD 80, to sound an alarm from the speaker 81, and to initiate the process of increasing electricity from the generator 55.

Also in this state, since electric power is supplied from the auxiliary battery 73 through the relay contact points 85 to the fuel supply system 12, the igniter 35 b, and the engine control unit 46, it is possible to reduce power losses due to internal resistance. For example, as shown in FIG. 6, there are no diodes in the connection between the auxiliary batter 73 and the fuel supply system 12. While diodes may be used in some aspects, in the aspects that do not include diodes, the voltage drop across the diodes may be removed with the diodes, thus reducing the power losses in the system.

When the output voltage Vp is higher than the broken wire threshold voltage Vpc, the propulsion battery 71 is charged with electricity from the generator 55, and the battery's 71 charged voltage Vp becomes greater than the threshold voltage Vpt. When the propulsion battery voltage Vp becomes greater than the threshold voltage Vpt, the process shown in FIG. 7 moves from step S2 to step S11. Since the battery anomaly flag FS is set to “1,” the process goes to step S12. If the output voltage Vp is lower than the threshold voltage Vpth, which is higher than the threshold voltage Vpt, the process moves to step S15 to maintain electric power supply from the auxiliary battery 73.

When the charged voltage Vp of the propulsion battery 71 exceeds the threshold voltage Vpth, the process goes from step S12 to step S13 to set the battery anomaly flag FS to “0.” The process moves to step S14, which deactivates the relay coil 86, bringing the movable contact point tm to the normally closed contact point tnc in order to resume power supply from the propulsion battery 71 to the fuel supply system 12, the igniter 35 b, the engine control unit 46, and the shift control unit 60. Providing a hysteresis characteristic as described above to resume electric power supply from the propulsion battery 71 when the charged voltage Vp of the propulsion battery 71 lowers below the threshold voltage Vpt (not attributable to a broken wire or short circuit) and when the charged voltage Vp of the propulsion battery 71 exceeds the threshold voltage Vpth, which is higher than the threshold voltage Vpt, may increase the stability of the power supply while avoiding the relay contact points 85 of the control relay 87 from falling into hunting state.

As shown in FIG. 7, if the propulsion battery 71 and auxiliary battery 73 are connected in parallel by mistake, the process moves from step S4 to step S5 to show a parallel connection anomaly display on the LCD 80 and sound an alarm from the speaker 81.

Although aspects described above may display the battery anomaly and give out an alarm when the charged voltage Vp of the propulsion battery 71 lowers, the invention is not limited to those aspects. Rather, the battery anomaly display and the alarm may be omitted. Additionally, while aspects described above are assumed to employ the LCD 80 as a displaying device, the displaying device is not limited to an LCD, but any other type of image displaying device may also be employed such as the CRT display, a displaying device for indicating the battery anomaly by illuminating light emitting diodes, for example. Likewise, the speaker 81 may be replaced with a buzzer. Further, while aspects above are described as adapted to give out an alarm sound from the speaker 81, this is not required. Rather, a speech synthesizing circuit may be provided to give out voice information corresponding to the abnormal state of the battery.

While some aspects are described as employing an outboard motor 3 the number of the outboard motor is not limited to one. When a plurality of outboard motors 3 is employed, while one auxiliary battery 73 may be sufficient, a plurality of propulsion batteries 71 may be used that correspond to the number of outboard motors 3. Accordingly, power from the auxiliary battery 73 may be supplied through diode D2 or the relay contact point to the respective outboard motors 3.

While some aspects do not supply power from the auxiliary battery 73 to the starter relay 52, other arrangements are also contemplated. In some aspects, the auxiliary battery 73 may supply power to the starter relay 52 while the starting switch is on. This may be particularly beneficial when the charged voltage Vp of the propulsion battery 71 is not higher than the threshold voltage Vpt.

While some aspects describe the engine 3E of the outboard motor 3 as a four-stroke cycle, fuel injection type, other engines may also be used. The aspects disclosed herein may also be applied to direct injection type and two-stroke cycle type of engines.

While the aspects describe the propulsion battery 71 as a single battery, this is not a limitation. The propulsion battery 71 may be made up of a plurality of batteries connected in parallel or series.

While the engine control unit 46 implements the battery anomaly control process in some aspects, the process may be implemented by other devices or components. For example, the shift control unit 60 may be provided with A/D conversion input terminals AD1 and AD2 so that the battery anomaly control process is implemented with the shift control unit 60.

Although the aspects described the engine control unit 46 and the shift control unit 60 as distinct, they may be replaced with a single control unit.

In one aspect, electric power supply from the auxiliary battery to the propulsion battery is made through the anomaly time power supply circuit when the propulsion battery becomes low in voltage. Therefore, an effect is provided that the propulsion device can be operated in a stabilized manner by securing electric power supplied from the auxiliary battery to the propulsion device. When the propulsion battery becomes low in voltage, the anomaly time power supply circuit causes the auxiliary battery to supply electric power to the propulsion battery, so that power may be supplied from the propulsion battery to the propulsion device in a stabilized manner (e.g., without relying solely on the generator).

Because the voltages of the propulsion battery and the auxiliary battery are individually detected with the voltage detecting means, it is possible to acquire the voltage drop state of the individual batteries from the detected voltages, and to detect incorrect, parallel connection made by mistake between the propulsion battery and the auxiliary battery. Therefore, when the above battery anomalies occur, it is possible for the anomaly processing section to carry out anomaly processing actions, such as increasing the ability of the generator charging the abnormal battery and giving out an alarm. Because the anomaly processing section gives out an alarm of low battery anomaly when it detects an anomaly, a low battery voltage, an effect is provided that it is possible to securely notify the boat operator of the low battery voltage so that checkup, replacement, or the like of the battery is made securely when the boat comes back to the harbor.

The voltages of the propulsion battery and the auxiliary battery are detected to make it possible to determine the presence of a parallel connection anomaly, parallel connection of both batteries made by mistake, when variations of the voltages are in agreement. Thus, an effect is provided that it is possible to accurately detect the parallel connection anomaly of the batteries. It is possible to supply electric power of the auxiliary battery when the voltage of the propulsion battery lowers by means of a simple constitution of the anomaly time power supply circuit in which both the batteries are interconnected through a pair of diodes for preventing electric power from flowing around.

The relay switch may be configured to be off when the propulsion battery is normal, thereby shutting off electric power supply from the auxiliary battery to the propulsion battery, and to be on by sending a control signal to the relay switch when the voltage of the propulsion battery lowers, thereby making electric power supply from the auxiliary battery to the propulsion battery. Because it is only to interpose a switch contact point in the power supply route from the auxiliary battery to the propulsion battery, an effect is provided that it is possible to reduce electric power loss without causing a voltage drop at the switch contact point. Because the relay switch for supplying electric power from the auxiliary battery to the propulsion battery is turned on by a control signal outputted from the anomaly processing section when a voltage drop of the propulsion battery is detected, the auxiliary battery is normally separated completely from the propulsion battery. Therefore, an effect is provided that electric power supply from the auxiliary battery to the propulsion battery is made possible only when the voltage of the propulsion battery lowers.

The power source device for the boat may further be adapted such that the anomaly processing section gives out an alarm of low voltage anomaly for the battery in question when a low voltage is detected either in the propulsion battery or in the auxiliary battery. Accordingly, because the anomaly processing section gives out an alarm of low battery anomaly when it detects an anomaly, a low battery voltage, it is possible to securely notify the boat operator of the low battery voltage so that checkup, replacement, or the like, of the battery is made securely when the boat comes back to the harbor.

In accordance with one aspect, the anomaly processing section may be adapted to detect a parallel connection anomaly of the propulsion battery and the auxiliary battery based on the voltages of both batteries. The voltages of the propulsion battery and the auxiliary battery may be detected to make it possible to determine the presence of a parallel connection anomaly in which both batteries are connected in parallel by mistake when voltage variations are in agreement. Thus, it is possible to securely detect the parallel connection anomaly of the batteries.

In accordance with another aspect, the anomaly time power supply circuit may be configured such that the positive pole side of the auxiliary battery is connected to the positive pole side of the propulsion battery through a pair of diodes to prevent electric power from flowing around from one to the other of the propulsion battery and the auxiliary battery. This may make it possible to supply electric power of the auxiliary battery when the voltage of the propulsion battery lowers by means of a simple constitution of the anomaly time power supply circuit in which both the batteries are interconnected through a pair of diodes for preventing electric power from flowing around.

In accordance with another aspect, the anomaly time power supply circuit may be provided with a relay switch for connecting the positive pole side of the auxiliary battery to the positive pole side of the propulsion battery by the input of a control signal. The supply circuit may be adapted to control the relay switch to be off when the propulsion battery is normal, thereby shutting off electric power supply from the auxiliary battery to the propulsion battery, and to be on by sending a control signal to the relay switch when the voltage of the propulsion battery lowers, thereby making electric power supply from the auxiliary battery to the propulsion battery. Because it is merely to interpose a switch contact point in the power supply route from the auxiliary battery to the propulsion battery, it is possible to reduce electric power loss without causing a voltage drop at the switch contact point.

In accordance with another aspect, the anomaly time power supply circuit may be provided with a relay switch for connecting the positive pole side of the auxiliary battery to the positive pole side of the propulsion battery, and the relay switch is driven with a control signal outputted from the anomaly processing section when a low voltage of the propulsion battery is detected. The relay switch for supplying electric power from the auxiliary battery to the propulsion battery may be turned on by a control signal outputted from the anomaly processing section when a voltage drop of the propulsion battery is detected. The auxiliary battery is normally separated completely from the propulsion battery so that electric power supply from the auxiliary battery to the propulsion battery is made possible only when the voltage of the propulsion battery lowers.

Although the present invention has been disclosed in the context of certain preferred aspects and examples, it will be understood by those skilled in the art that the present invention extends beyond the specifically disclosed aspects to other alternative aspects and/or uses of the present invention and obvious modifications and equivalents thereof. In addition, while a number of variations of the present invention have been shown and described in detail, other modifications, which are within the scope of present invention, will be readily apparent to those of skill in the art based upon this disclosure. It is also contemplated that various combinations or subcombinations of the specific features and aspects of the aspects may be made and still fall within the scope of the present invention. Accordingly, it should be understood that various features and aspects of the disclosed aspects can be combined with or substituted for one another in order to form varying modes of the present invention. Thus, it is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed aspects described above, but should be determined only by a fair reading of the claims that follow. 

1. A power source device for a boat comprising: a propulsion battery for supplying electric power to a propulsion device of the boat; an auxiliary battery for supplying electric power to other devices of the boat; and an anomaly power supply circuit for supplying electric power from the auxiliary battery when a voltage drop occurs in the propulsion battery.
 2. A power source device for a boat comprising: a propulsion battery for supplying electric power to the propulsion device of the boat; an auxiliary battery for supplying electric power to auxiliary devices of the boat; an anomaly power supply circuit for supplying electric power from the auxiliary battery when voltage drop occurs in the propulsion battery; a voltage detecting means for individually detecting the voltages of the propulsion battery and the auxiliary battery; and an anomaly processing section for performing an anomaly processing action when a battery anomaly is detected based on the voltages of the propulsion battery and the auxiliary battery detected with the voltage detecting means.
 3. The power source device of claim 2, wherein the anomaly processing section is adapted to give out a low voltage anomaly alarm for either the propulsion battery or the auxiliary battery when a low voltage is detected for the battery in question.
 4. The power source device of claim 2, wherein the anomaly processing section is adapted to detect a parallel connection anomaly of the propulsion battery and the auxiliary battery based on the voltages of both batteries.
 5. The power source device of claim 2, wherein the anomaly power supply circuit is adapted that a positive pole side of the auxiliary battery is connected to a positive pole side of the propulsion battery through a pair of diodes to prevent roundabout current from flowing from one to the other of the propulsion battery and the auxiliary battery.
 6. The power source device of claim 2, wherein the anomaly power supply circuit is provided with a relay switch for connecting the positive pole side of the auxiliary battery to the positive pole side of the propulsion battery by the input of a control signal.
 7. The power source device of claim 2, wherein the anomaly power supply circuit is provided with a relay switch for connecting the positive pole side of the auxiliary battery to the positive pole side of the propulsion battery, and the relay switch is actuated with a control signal outputted from the anomaly processing section when a low voltage of the propulsion battery is detected.
 8. A power source device for a boat, the power source device comprising: a propulsion battery for supplying electric power to a propulsion device of the boat; an auxiliary battery for supplying electric power to auxiliaries of the boat; a power supply circuit for supplying electric power from the auxiliary battery when a voltage drop occurs in the propulsion battery; and an anomaly processing section configured to detect voltages of the propulsion battery and the auxiliary battery, the anomaly processing section being configured to detect at least one of the following power source anomalies: a low battery voltage in the auxiliary battery, a low battery voltage in the propulsion battery, a parallel connection, and a broken wire; wherein when the anomaly processing section detects a low battery voltage in the propulsion battery, the anomaly processing section increases the output of a generator.
 9. The power source device of claim 8, wherein the power supply circuit comprises a plurality of diodes configured to permit the auxiliary battery to supplement the propulsion battery when the propulsion battery falls below the voltage of the auxiliary battery.
 10. The power source device of claim 8, wherein the power supply circuit comprises a switch that is configured to place the auxiliary battery in connection with at least one of the components powered by the propulsion battery.
 11. The power source device of claim 8, wherein the propulsion battery is recharged by the increased generator output.
 12. The power source device of claim 8, wherein the anomaly processing section comprises a microprocessor.
 13. The power source device of claim 12, wherein the microprocessor is part of the engine control unit.
 14. The power source device of claim 12, wherein the microprocessor controls at least one operation of the engine.
 15. A method of controlling a boat's power supply when the boat has a plurality of batteries and a generator, the method comprising: detecting the voltage of a propulsion battery and comparing the detected voltage with a first threshold propulsion battery voltage; supplementing the voltage of the propulsion battery with the voltage of the auxiliary battery when the voltage of the propulsion battery falls below the first threshold propulsion battery voltage; determining whether a drop in propulsion battery voltage is caused by a broken wire or low battery voltage when the propulsion battery voltage falls below the first threshold propulsion battery voltage; and providing at least one of an audible and visual signal that either a low battery voltage or a broken wire and increased generator output when the cause of the drop in propulsion battery voltage is determined.
 16. The method of claim 15, wherein the auxiliary battery supplements the propulsion battery when the propulsion battery falls below the voltage of the auxiliary battery.
 17. The method of claim 15, wherein the auxiliary battery supplements the propulsion battery when a power supply circuit is switched to connect the auxiliary battery with at least one component powered by the propulsion battery.
 18. The method of claim 15, wherein the determination of the drop in propulsion battery voltage is made by comparing the propulsion battery voltage with a broken wire threshold voltage.
 19. The method of claim 15, further comprising detecting the voltage of an auxiliary battery and comparing the detected voltage with a threshold auxiliary battery voltage.
 20. The method of claim 16, wherein at least one of either an audible or visual signal is provided to indicate low auxiliary battery voltage when the auxiliary battery voltage falls below the threshold auxiliary battery voltage.
 21. The method of claim 16, wherein the difference between propulsion battery and auxiliary battery is compared to a difference threshold voltage.
 22. The method of claim 21, wherein at least one of either an audible or visual signal is provided indicating a parallel connection if the difference between the propulsion battery and the auxiliary battery falls below the difference threshold voltage.
 23. The method of claim 15, wherein the auxiliary battery supplements the propulsion battery until the propulsion battery voltage is greater than a second threshold propulsion battery voltage, the second threshold propulsion battery voltage being greater than the threshold propulsion battery voltage.
 24. A power source device for a boat, the power source device comprising: a propulsion battery for supplying electric power to a propulsion device of the boat; an auxiliary battery for supplying electric power to auxiliaries of the boat; means for supplying electric power from the auxiliary battery when a voltage drop occurs in the propulsion battery; means for detecting at least one of the following power source anomalies: a low battery voltage in the auxiliary battery, a low battery voltage in the propulsion battery, a parallel connection, and a broken wire; and means for increasing the output of a generator when a low battery voltage is detected in the propulsion battery. 